1. Field of the Invention
The present invention relates to a method and to an apparatus for accurate positioning of a magnetic head to at least one track of a moving recording medium in a magnetic layer memory, wherein the magnetic head is a combined magnetic head and includes at least one write head for recording signals on the recording medium and at least one read head for reading signals from the recording medium.
2. Description of the Prior Art
In a recording of signals, particularly data on a moving recording medium in a magnetic layer memory system, it is notoriously known in the art to employ a combined magnetic head that contains at least one write head and at least one read head. The storage system can be constructed, for example, as a magnetic tape recorder, as a magnetic disk memory, or as a diskette memory. The data are recorded on one or more tracks of the recording medium for example a magnetic tape, a magnetic disk or a diskette, with the write head and are read therefrom with the read head.
In a recording of data with a high packing or storage density in a plurality of parallel tracks, it is important, first of all, to increase the data set to be stored in the longitudinal direction of the tracks and, secondly, to increase the plurality of tracks on the recording medium. For this purpose, it is known to utilize a combined magnetic head having one or only a few write heads and one or only a few read heads and to then position the magnetic heads such that a write head and/or a read head comes to lie exactly on a respective desired track.
A method and an arrangement for the accurate positioning of a magnetic head to various tracks of a recording medium are disclosed, for example, in U.S. Pat. No. 4,866,548, fully incorporated herein by this reference. For positioning a magnetic head which is displaceable perpendicular to the running direction of the recording medium, a position value and, potentially, a correction value are calculated for each track in this known method, these values being supplied in common to a control device. The control device generates control signals therefrom for a positioning device for displacing the magnetic head. This known method leads to a drive of which the magnetic head position is dependent on the position values and on the appertaining correction values. A regulation of the positioning is not provided in this method.
The British Patent application 1 470 735 discloses an arrangement for regulating the track position of a magnetic head on a track of moving recording medium. In this known arrangement, a magneto-resistive read head that is fashioned wider than the track is provided in the magnetic head. The read head contains a center tap and a control signal for displacement of the magnetic head perpendicular to the moving direction of the recording medium is generated from the difference between the output signals of the two halves of the read head formed by the center tap. In this known arrangement, therefore, a magneto-resistive read head is required that is normally not available in standard magnetic heads.